Could the Chilling Process be Optimized to Decrease Campylobacter on Broiler Carcasses?

Introduction: Campylobacter is one of the most common causes of diarrheal illness in many industrialized countries. Most cases of campylobacteriosis are associated with eating raw or undercooked poultry meat or from cross-contamination of other foods by these items. Risk assessment studies have indicated that campylobacteriosis associated with chicken products may be reduced 30 times by a 2-log reduction of Campylobacter concentration on carcasses.

Purpose: The objective of this work is to define chilling conditions allowing to reducing Campylobacter levels on poultry carcasses.

Methods: This study was set up to investigate four major parameters in the chilling process (temperature, duration, air velocity and initial concentration of Campylobacter) individually and in interaction on the behavior of Campylobacter using the Doehlert shell design. Three experimental designs were performed using a chilling prototype. Chicken legs were artificially contaminated before chilling. After chilling, Campylobacter counts were conducted in accordance with the ISO standard 10272-2.

Results: The maximum contamination reduction reached a rate of 63% corresponding to a reduction of 1.5 log CFU/g. Duration of chilling (P = 0.04) and initial concentration (P = 0.03) had significant effects: the reduction rate increased when the duration increased and the initial concentration decreased. An interaction between temperature and initial concentration had also a significant effect (P = 0.01) on Campylobacter contamination. If initial concentration was 10³ CFU/g, temperature (P = 0.0045) had a significant effect: the reduction rate decreased when the temperature increased. Interaction between temperature and air velocity had also a significant effect (P = 0.007) on Campylobacter contamination.

Significance: The most important result is that carcasses presenting more than 10³ CFU/g of Campylobacter would not be significantly decontaminated during the chilling process. Moreover this work shows that a chilling process with low temperature can significantly reduce the bacterial load on chicken carcasses presenting not more than 10³ CFU/g.